This collection of mathematical articles covers a broad range of delightful topics in pure and applied mathematics. It is written in an expository style, making it accessible to everyone with a general interest in mathematics. There are articles about renowned mathematicians and about the history of some key ideas in maths. The importance of mathematics in the modern world is illustrated by applications in engineering, technology, astronomy, music and the visual arts. Reading mathematics is best done in small steps. The articles are all short, and they can be read in arbitrary order. Some articles are purely descriptive. Others go deeper and are at a more advanced mathematical level. Approximately half the articles have appeared in the author's regular column "That's Maths" in The Irish Times. Others have been posted to his mathematical blog, thatsmaths.com. All articles have been fully revised for this book. This is the second collection under the rubric "That's Maths". The first collection, published in 2016, was very favourably reviewed. The author has succeeded in bringing out the amazing beauty of mathematics and its utility in so many areas of our lives. The book should be appreciated by anyone with an interest in mathematics and science. In particular, teachers of these subjects, at both school and university level, should find a wealth of material to supplement and invigorate their classes.